Answer:Two more hydrogen atoms will be required
Explanation:
A carbon atom has 4 valence electrons in its outermost shell,thus it can form 4 covalent bonds.Two pairs of electrons are shared in a double bond between C-C atom.two more electrons are left which is shared with two hydrogen atoms.
Since water is already at 100<span>°C all the energy is used to evaporate it.
Now we can calculate how many </span>mols of water are evaporated with 820kJ.

We calculated that we got 20 mols of water evaporated. Now, all we have to do is find how many grams is a mol of water. Molar mass of water is <span>20.16 g/mol.
</span>The final answer is:
The moving car experiences unbalanced forces when applying brakes; when a car is slowing as it reaches a stop light.
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Explanation:
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When the car driver applies brakes to a car in order to stop, an unbalanced force is applied to the car. The speed of car gradually reduces and there’s a decrease in acceleration; a net force acts on it.
Options A and D has a box and a rocket always in a rest position. A car with cruise control is an adaptable speed setting for a vehicle which helps it to maintain a fairly constant speed. Constant velocity gives zero acceleration and hence no considerable unbalanced forces appear.
7 strong acids are strong electrolytesHCl, HBr, HI, HNO3, HCIO3, HCIO4, and H2SO4
3 strong bases are strong electrolytes<span>OH, KOH, and NaOH</span>